Generics iOS Swift UIKit

Instantiating view controllers from UIStoryboard on iOS

There are several ways how to create user interfaces on iOS: programmatically, xib per view or using storyboard for multiple views. Personally I tend to use xibs and programmatically created layouts more but sometimes I also use UIStoryboard – depends on the situation on hand. Therefore I like to present two small additions to UIStoryboard API what makes instantiating view controllers more compact and convenient to use.

let storyboard = UIStoryboard(name: "Main", bundle: nil)
let viewController = storyboard.instantiateViewController(withIdentifier: "contacts") as! ContactsViewController

The approach I would like to present is a generic instantiate view controller method. It implies that in storyboard, the view controller’s identifier is set to the name of the view controller class.

When Storyboard ID for the view controller is set to the class name, it is now easy to derive the identifier from a type. It should be noted that in Swift, NSStringFromClass returns string with format <module name>.<class name>. Therefore it required to parse the returned string and taking only the class name part.

extension UIStoryboard {
func instantiateViewController<T: UIViewController>(withType type: T.Type) -> T {
let className = NSStringFromClass(type).split(separator: ".").last!
return instantiateViewController(withIdentifier: String(className)) as! T

In addition, with convenience method for getting storyboard, we can get to end result which is more compact and also avoids having identifier strings in the code.

extension UIStoryboard {
class var main: UIStoryboard {
return UIStoryboard(name: "Main", bundle: nil)
let viewController = UIStoryboard.main.instantiateViewController(withType: ContactsViewController.self)

If this was helpful, please let me know on Mastodon@toomasvahter or Twitter @toomasvahter. Feel free to subscribe to RSS feed. Thank you for reading.

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